TORONTO - CanWest Global said today it is exercising its right to increase its equity in the joint company (with Goldman Sachs) that is acquiring Alliance Atlantis Communications Inc. ("Alliance Atlantis"), to $200 million. The proposed purchase was announced last month and still has to get past the regulator.CanWest's initial commitment to the venture was $132 million and it has the option to increase this commitment within 45 days of the original agreement. CanWest's equity will be directed to the subsidiary acquiring Alliance Atlantis's broadcasting division and will result in CanWest holding an economic position therein of approximately 29%, subject...